Senior members of the Northern Territory's legal fraternity are warning that mandatory sentencing in the Territory has negative effects, particularly on the Aboriginal community.

The NT leads not just Australia, but comes third in global rankings, after the United States and China, in terms of locking people behind bars.

Earlier this year the Territory Government increased minimum jail time for offenders while restricting judges' right to suspend sentences for certain offences.

Under the new laws, every first-time offender convicted of a violent offence faces three months in jail, and repeat offenders receive a 12-month sentence.

Across the country Indigenous people comprise more than a quarter of the prison population but in the Northern Territory it is closer to 90 per cent.

Vince Kelly, president of the Northern Territory Police Association, says those statistics are "depressing".

"Well I think those statistics at one level are pretty depressing. The fact of the matter is that we continue to fill the jails up. As I say the NT police, we are good at our job," he said.

"Has the NT community or society benefited from arresting people at that rate over the last 25 years? I guess [that's] a real question there.

"I think if you ask any operational cop out on the street, 'have things vastly changed?', particularly those of us who have been around 20-25 years would probably [say] no."

Mandatory sentencing targets biff merchants: Attorney-General

NT Attorney-General and former police officer John Elferink was the driving force behind the reintroduction of mandatory sentencing, and says the laws are necessary.

"We have run a number of what are called controversial policies, and they are controversial because they have said to individuals: 'you will be accountable for your actions'," Mr Elferink said.

We get criticised... because there is a significant number of Aboriginal people in custody... on the other side we are told you might be too lenient in terms of violent conduct.

Greg Smith, Northern Territory Magistrate

"And we have introduced mandatory sentencing for those biff merchants that go around the community thumping people."

But Priscilla Collins, chief executive of the North Australian Aboriginal Justice Agency, says there should be alternatives to prison sentencing.

"Yes, there are people who definitely do need to go to jail and we do agree with that. But when you've got at least 50 per cent of them in there for six months or less for minor offences, why are taxpayers paying $110,00 a year to keep them there?" she said.

NT Magistrate Greg Smith says it can be a difficult decision to make.

"We get criticised on one side of the fence because there is a significant number of Aboriginal people in custody," he said.

"On the other side we are told you might be too lenient in terms of violent conduct, so you are sort of caught between those two issues."